Method and apparatus for separating mixtures of fine grain materials

ABSTRACT

Installation for separating a mixture of particles of two different materials, one of which materials has an affinity for a gas into fractions in which with a cylindrical tank in one wall having a centrally positioned inlet stub for a mixture of the materials for separation, in the other end wall of the tank a centrally disposed outlet for part of the liquid together with one fraction of the mixture, a tangential liquid inlet stub near the central inlet stub and a tangential outlet stub near the other end wall thereof, said outlet stub adapted for discharging the part of the liquid together with the other fraction of the mixture and there being means for commingling the gas with the liquid introduced.

United States Patent 11 1 Pouillon 1 Sept. 18, 1973 METHOD AND APPARATUSFOR SEPARATING MIXTURES OF FINE GRAIN MATERIALS [75] Inventor: Emile R.J. Pouillon, Bruxelles,

Belgium [73] Assignee: Societe Anonyme Cribla, Brussel,

Belgium [22] Filed: June 17, 1970 [21] Appl. N0.: 46,931

[30] Foreign Application Priority Date June 18, 1969 Netherlands 6909273[52] US. Cl. 209/165, 209/168 [51] Int. Cl B0311 1/14 [58] Field ofSearch 209/168, 170, 162-165, 209/211, 155,173

[56] References Cited UNITED STATES PATENTS 2,543,689 2/1951 Driessen eta1. 209/172.5 2,726,766 12/1955 Rakowsky 209/211 2,778,499 ll1957Chamberlain et al. 209/170 X 2,843,265 7/1958 Rakowsky 209/211 X2,879,889 3/1959 Rakowsky 209/173 2,999,593 9/1961 Stern 209/1443,219,186 11/1965 Polhemus et a1. 209/211 X 3,477,569 11/1969 Klein etal. 209/144 FOREIGN PATENTS OR APPLICATIONS 1,022,375 3/1953 France209/211 1,158,461 12/1963 Germany 209/168 Primary Examiner-Frank W.Lutter Assistant Examiner-Ralph J. Hill Attorney-Snyder and Butrum [57]ABSTRACT Installation for separating a mixture of particles of twodifferent materials, one of which materials has an affinity for a gasinto fractions in which with a cylindrical tank in one wall having acentrally positioned inlet stub for a mixture of the materials forseparation, in the other end wall of the tank a centrally disposedoutlet for part of the liquid together with one fraction of the mixture,a tangential liquid inlet stub near the central inlet stub and atangential outlet stub near the other end wall thereof, said outlet stubadapted for discharging the part of the liquid together with the otherfraction of the mixture and there being means for commingling the gaswith the liquid introduced.

1 Claim, No Drawings METHOD AND APPARATUS FOR SEPARATING MIXTURES OFFINE GRAIN MATERIALS The invention relates to a method of separating amixture of particles of two different materials on the basis of adifference in affinity of the two materials for a gas, by means of aliquid which is brought into rapid rotation, the gas being dispersed inthe liquid. Under the influence of the field of centrifugal forceoccuring in the rotating liquid, two zones form therein, one of whichcontains a heavy fraction of the mixture for separation while the otherzone contains a light fraction of the mixture.

As a result of the presence of the finely divided gas in the liquid,good separation into the two fractions of the fine-grain materials isobtained.

The object of the invention is to provide a method which gives verysharp separation of the two fractions. According to the invention themixture of particles of materials for separation can be fed in adirection axially of the resulting eddy through the rotation gasJiquiddispersion. v

The invention also relates to an installation for separating a mixtureof particles of materials of different types into fractions by themethod described above;

According to the invention, a cylindrical tank is provided, one end wallof which has a centrally positioned inlet stub, to which means areconnected for supplying a mixture of the materials for separation, theother end wall of the tank having a centrally disposed outlet connectedto means for discharging part of the liquid together with one fractionof the mixture, a liquid inlet stub connected tangentially to theperpheral wall of the tank is disposed near the central inlet stub and atangential outlet stub is connected to the perpheral wall of the tanknear theother end wall thereof, the outlet stub being connected to themeans for discharging the part of the liquid together with the otherfraction of the mixture. With sucha construction of the installation,the mixture for separating must move axially through the rotatingliquid.

in a very simple embodiment of the installation according to theinvention, the means for supplying the end wall 20. Inlet stub 16 isconnected via a pipe 22 to the delivery of a pump 23. aA pipe 24connects the intake of the pump 23 to reservoir 25. The latter maycontain the liquid, e.g. water, which is to be supplied to the tank 15.A pipe 26 also leads into the intake pipe 24 and air can be drawn inthrough said pipe 26. A container 27 for the materials which are to beseparated, is connected to the inlet stub 19 'via a pipe 28. Outlet stub21 is connected via a pipe 29 to a tank 30 to receive the light fractionformed by those constituents of the mixture to which the air hasadhered, together with a part of the liquid. The outlet stub 17 isconnected via a pipe 31 to a tank 32 to receive another part of theliquid together with the other fraction.

The installation operates as follows. The water, to-

, gether with the air drawn in via pipe 26, is fed from the gas-liquiddispersion may comprise a pump, whose inlet is provided with means forsupplying gas to the liquid. Since the gas and the liquid flow throughthe pump together, good dispersion of the gas in the liquid is obtainedin the pump. Thus no extra mixer is required.

The invention will be explained in detail in the following descriptionof one exemplified embodiment with reference to the drawing whichdiagrammatically illustrates an installation accordingto the invention.

The installation comprises a cylindrical tank 15 provided with atangential inlet stub 16 leading into the peripheral wall of the tankand disposed near one end thereof, while a tangential outlet stub 17 isdisposed near the other end of said tank. A central inlet stub 19 issituated in the end wall 18 near the inlet stub 16 while a centraloutlet stub 21 is situated in the other tank 25 to the pump 23, the airand the liquid being intimately mixed. The resulting dispersion is fedvia the pipe 22 to the tank 15. As a result of the axial introductionthe dispersion receives a rapid rotation in these conditions. Themixture for separation is supplied centrally via the pipe 28. Thismixture moves through the tank 15 axially with respect to the directionof movement of the rotating liquid. The heavy fraction moves outwardsand is discharged via stub 17 and pipe 31 to tank 32. Part of the liquidtogether with the light fraction enters the tank 30 via the stub 21 andpipe 29.

As a result of the addition of air to the liquid, causing finely dividedair to be present in the liquid, very good separation is obtained. Sincethe material particles have to move axially through the rotating liquid,all the particles come into contact with air particles which can adhereto certain material particles, so that very good separation is obtained.

It should also be noted that in the case of a mixture of particles ofdifferent specific gravity, the particles having the greater specificgravity can subsequently form the lighter fraction in the liquid gasdispersion because the gas bubbles have a greater affinity for theseparticles than for the particles which of themselves are of lighterspecific gravity.

I claim:

1. A method of separating a mixture of particles of two differentmaterials, only one of which materials has an affinity for a gas, whichcomprises the steps of:

a. feeding the mixture into one end of an elongate chamber in axialdirection;

b. tangentially introducing liquid into said one end of the chamber;

c. tangentially'withdrawing liquid and material particles from theotherend of said chamber;

d. axially withdrawing liquid and material particles from said other endof said chamber; and

e. during step (b), commingling said gas with the liquid introduced sothat the material'particles withdrawn in step (d) are of said onematerial and the material particles withdrawn in step (c) are of theother material.

1. A method of separating a mixture of particles of two differentmaterials, only one of which materials has an affinity for a gas, whichcomprises the steps of: a. feeding the mixture into one end of anelongate chamber in axial direction; b. tangentially introducing liquidinto said one end of the chamber; c. tangentially withdrawing liquid andmaterial particles from the other end of said chamber; d. axiallywithdrawing liquid and material particles from said other end of saidchamber; and e. during step (b), commingling said gas with the liquidintroduced so that the material particles withdrawn in step (d) are ofsaid one material and the material particles withdrawn in step (c) areof the other material.